10 replies to this topic

[Re-enactor]

Thought I'd see what people think of this..

At a re-enactment show I attended I was helping issue black powder and wireup pyros for the displays. All of the pyros consisted of small amounts (<25g) of BP ignited by fuse or electric match loose packed (in plastic cups or thin plastic bags) with loose plain flour on top- this was to simulate cannon hits. The show went without a hitch. However weks later discussing the event (online) with others who were present I foud myself and the team criticised on the basis that flour is lammable and that it was mere luck that none of the pyros caused injury.

The team in charge (who taught me how to prepare those pyros) had been trained by professionals and in non-battlefield use I have yet to encounter the flour igniting when used in this way (despite dozens of tests). However in case this comes up again I thought I'd see what you folks thought.

I think that there is a basis for what is said but only when compression/ larger amounts of BP are used. I can say that powdered milk certainly does do this (used when I did want a fireball effect!).

[digger]

Thought I'd see what people think of this..

At a re-enactment show I attended I was helping issue black powder and wireup pyros for the displays. All of the pyros consisted of small amounts (<25g) of BP ignited by fuse or electric match loose packed (in plastic cups or thin plastic bags) with loose plain flour on top- this was to simulate cannon hits. The show went without a hitch. However weks later discussing the event (online) with others who were present I foud myself and the team criticised on the basis that flour is lammable and that it was mere luck that none of the pyros caused injury.

The team in charge (who taught me how to prepare those pyros) had been trained by professionals and in non-battlefield use I have yet to encounter the flour igniting when used in this way (despite dozens of tests). However in case this comes up again I thought I'd see what you folks thought.

I think that there is a basis for what is said but only when compression/ larger amounts of BP are used. I can say that powdered milk certainly does do this (used when I did want a fireball effect!).

Hi. I have done some work for a re-enactment group (WW2 stuff). They don't use flour, not necessarily due to ignition issues (although a definite possibility), mainly as there are better things to use from an effects point of view (and cheaper).

The thing that is most often used is what is called bleaching clay (a type of fullers earth). This can be had for as little as £400 per tonne delivered. I get it at work for free when one of our powder transfer valves fail (often).

So send me a PM and we can discuss getting a bit sent out to you to play with.

Cheers

D

[whoof]

Flour can indeed explode.
I have seen videos of tests where flour dust blown into a room with air could explode with enough force to destroy a building.
Only a few grammes was required.

[helix]

Dispersed flour dust can certainally behave as an explosive, the risk is taken seriously in flour mills for sure. The dust needs to be well dispersed to explode I think but I'm sure that serveral flour mills have been razed to the ground in this manner.

I don't know the explosive limits of flour dust - perhaps it needs to be more widely dispersed than milk powder to burn also I'd guess its calorific value would be a lot less than powdered milk.

[digger]

I'd guess its calorific value would be a lot less than powdered milk.

Yep starch is about 4 calories per gram and fat 7 calories per gram. But not the whole story, have read through a copy of Sax's hazardous properties of materials for LEL and UEL (lower and upper explosive limits) along with ignition energies required.

[Re-enactor]

Interesting stuff- @ digger had heard about fullers earth. Might give this a try next season.

I don't use flour myself as it does not seem to ad much to the effect but as I work with those who do thought it worth more discussion. Interestingly one reason I don't use it is in case of people nearby who are lactose intolerant (amazing the stuff you come up with through risk assessment!).

[Peret]

I dimly remember a flour mill explosion happening when I was a small child, so it must have been devastating indeed for me to have heard of it. I've since read that old-time flour mills were only operated in daylight hours, since nobody dared take a lighted candle inside one.

[Mortartube]

Flour can indeed be explosive as can brick dust and cement. Many things will burn if finely divided and ignited. Bags of bark chippings from the garden centre are good to blow in the air as they are cheap, softish and biodegradeable.

Try wrapping some flour in muslin and shaking it over a lit candle on the ground. Wear fireproof overalls and gloves to save getting burnt,

Flour explosion

[Arthur Brown]

It's explosives so NOTHING is safe or risk free, powdered organic materials can often be flammable, dried milk is used to create fireballs and flour can be ignited, however your safety plans should account for surviving the worst case - a fireball! So distance is your friend.

I fail to see how brick dust or cement (which both get processed at over 1000C can be flammable -even slightly. Possibly a suitable material for dust clouds is garden centre peat or compost -and usually you don't have to clear it up too much either. However nothing is safe here inorganic dusts can be irritating and organic things like soil/peat etc can contain bio things that may be nasty. again distance is your friend.

[Re-enactor]

interesting stuff guys, if we were to use any material (currently just using the BP) it needs to be safe both from ignition and chemically sound (cement is not great in eyes/ respiratory system). Fullers earth sounds worth a closer look as does compost so far.

[barra69]

Flour is used in advanced Dems (mil) as the fuel in dust explosions, however certain manufacturing criteria need to be met which are well beyond the remit of general pyrotechnics.